Figure 1: Model system and proposed experimental setups.
From: Suppression of population transport and control of exciton distributions by entangled photons
(a) The bacterial RC and its electronic level scheme. The active branch where charge separation takes place is shown in blue, the inactive in red. The model has 12 e-states and 41 f-states, labelled as e1,…, e12 and f1,…, f41. (b) The proposed setup for entangled photons: a pump photon of frequency ωp is down-converted into two photons with frequencies ω1 and ω2, and directed onto the bacterial RC. We consider type-II down conversion, which means one of the photons is created along the ordinary axis of the crystal, and the other one along the extraordinary axis46. The different group velocities along these two axes create a time delay between the two-photon wavepacket—the entanglement time T. Owing to energy conservation, the two photons are entangled in their frequencies ωp=ω1+ω2: both the green and red beam may have a very broad bandwidth, but as soon as the frequency of one of the two photons is measured, the wavefunction of the other beam collapses, and the frequency of the photon is sharply defined as well. By selecting the angles θ1 and θ2, one can tune the central frequencies of the entangled wavepackets. (c) The setup for chirped pulses: two laser pulses with frequencies ω1 and ω2 are stretched in time by grating pairs in an anti-correlated manner, thus inducing frequency anti-correlations.
